Abstract Mass cytometry is a revolutionary technology that allows multi-parameter analysis of single cells in a manner similar to flow cytometry, but with a 3-4 fold increase in dimensionality. The CyTOF Helios is the most advanced mass cytometer system, which functions by adapting to the existing CyTOF2 system. By using metal ions rather than fluorescence tags, CyTOF can measure 50+ parameters simultaneously with minimal signal overlap and a need for signal compensation. In comparison, traditional flow cytometry can only measure 12-18 markers simultaneously on single cells. Although our CyTOF2 system is already producing high quality data, to improve the data-producing quality and efficiency, the proposed upgrade to the Helios system is a necessary step to allow this valuable equipment to function optimally. This proposal seeks support for the acquisition of CyTOF Helios system for the use at the Philadelphia VA Medical Center (PVAMC).